WASHINGTON — Former presidential candidate Mitt Romney seemed to imply Friday that electing Donald Trump president could worsen racism and bigotry in the United States, hurting the “heart and character of America.”

Romney, the 2012 Republican nominee and frequent critic of the billionaire’s campaign, told CNN he didn’t “want to see trickle-down racism" in the United States.

"I don't want to see a president of the United States saying things which change the character of the generations of Americans that are following,” Romney said. “Presidents have an impact on the nature of our nation, and trickle-down racism, trickle-down bigotry, trickle-down misogyny, all these things are extraordinarily dangerous to the heart and character of America."

Trump, the presumptive presidential nominee, responded on his Twitter account Saturday by saying Romney “chocked like a dog” in his failed run for the presidency four years ago.

“Now he calls me racist-but I am least racist person there is,” Trump tweeted. “Don King, and so many other African Americans who know me well and endorsed me, would not have done so if they thought I was a racist!”

Trump has been heavily criticized by Democrats and watched as Republicans have distanced themselves from racially charged comments he made recently about a judge overseeing fraud lawsuits against the former Trump University.

Trump said U.S. District Judge Gonzalo Curiel might be biased against him because of Curiel's "Mexican heritage," comments that drew accusations of racism from across the political spectrum. He said his own previous characterizations of Mexican immigrants as rapists and criminals, along with his pledge to build a wall along the U.S.-Mexico border, might make it impossible for Curiel to be impartial in the fraud case.

Trump responded this week that his comments on Curiel were "misconstrued as a categorical attack against people of Mexican heritage.”